Air pump or compressor



June 2, 1942. c. H. DUFFY 2,234,645

AIR PUMP OR COMPRESSOR Filed Jan. 27, 1941 2 Sheets-Sheet l ATTORNEYJune 2, 1942. H DUFFY 2,284,645

AIR PUMP OR COMPRESSOR Filed Jan. 27, 1941 2 Sheets-Sheet 2 ATTORNEYPatented June 2, 1942 UNITED STATES PATENT OFFICE 2,284,845 'AIR row oncomanssoa v Charles Hush Duly, Miami. Fla. Application January 27, 1941,Serial No. avarzo is (or 230-190) (Granted under the act)! March 3,

amended April 30, 1928; 370 0. G. 757) The invention described hereinmay be manulectured and used by or for theGovernment of the UnitedStates for governmental purposes without the payment to me of anyroyalty thereon in accordance with the provisions of the act of April30, 1928 (Ch. 460. 45 Stat. L. 467).

This invention relates to air-pumps or compressors, and has for itsobject to provide-a device of this class which is particularlyapplicable for laboratory use, or for aerating the water in small tanksor the like where a small portable electrically driven pump orcompressor is desirable.

The invention consists of the pump which dispenses with an air intakevalve, and in the piston and rod arrangement, and in the constructionfor mounting the pump directly on the electric driving motor; while inone embodiment, the invention consists of the frictional drivingmechanism for driving the pump.

Referring to the accopanying drawings:

Fig. 1 is a front elevation of one example of the invention showing thesame directly mounted on the electric driving motor, some of the partsof the pump being shown in vertical section.

Fig. 2 is a side elevation of the same.

Fig. 3 is a somewhat diagrammatic front elevation of a modifiedconstruction illustrating the friction drive mechanism for actuating thepump.

Fig. 4 is a fragmentary top plan view of the same, the friction ring ormember being shown in horizontal section.

Figs, 5, 6, 7 and 8 are diagrammatic views illustrating the positionswhich the piston and rod assume at the four principal points in acomplete cycle.

Like numerals of reference indicate the same part throughout the severalfigures.

For a quicker understanding of the invention, it is, perhaps, preferableto describe first the pump or piston action as illustrated in thediagrammatic Figures 5, 6, 7 and 8.

In these views, I indicates the rotating pump shaft, 2' the crank, and 3the crank-pin. 4 indicates the piston rod, 5 indicates the piston and 6the wall of the pump cylinder.

It will be noted that the piston rod is rigidly connected to thepistonso that the piston assumes various angular positions within the pumpcylinder as the crank-pin 3 revolves about the pump shaft I, and alsothat the piston rod 4 may be bent out of a straight line so that whenthe crank-pin 3 is on upper and lower dead centers as shown in Figs. 6and 8, the plane of the piston 5 is disposed angularly to the verticalaxis of the pump cylinder 6, and not perpendicularly to said 7 such asleather, as will be axis as would be the case if the piston rod 4 werestraight. The extent of the angularity which the piston will assume withrespect to the cylinder 5' will depend, of course, upon the amount 0 thebend imparted to ,the piston rod. I

While for successful operation the exact amount that the piston rod isbent out of a straight line is not critical, I have found that theamount 01' bend illustrated in the diagrammatic Figures 5 to 8 is verysatisfactory. In this instance, it will be seen by reference to Fig. 7,that a line projected downwardly from the center of the piston 5 andperpendicular to the plane of the piston, will exactly bisect the crank2, at the point 1 which is the mid-point of the crank 2. This causes theangularity of the rigidly connected piston 5 with respect to thecylinder 6 when the crank 2 is horizontal on its upstroke to be exactlythe same as it would be if the piston rod were straight and the lengthof the crank 2 were one-half the actual length illustrated. It

will also be seen that by reason of this amount of bend imparted to thepiston rod 4, the angularity of the piston 5 with respect to thevertical axis of the cylinder 6 is the same when the crank 2 is onbottom dead center, as in Fig. 6; on top dead center as in Fig. 8, andhorizontal on its upstroke as in Fig. 7.

But comparing Fig. 7 with Fig. 5, which illustrates the angularity ofthe piston 5 when the crank 2 is horizontal on the down-stroke, a verydecided difference will be seen. In the case of Fig. 5, the bend in thepiston-rod 4 has disposed the plane of the piston 5 at the same anglewith relation to the vertical axis of the cylinder 5, as would be thecase if the throw of the crank 3 were one and one-half times longer thanit is actually illustrated to be.

With this description of the preferred extent of bending the piston-rod4 of the rigidly connected piston 5, the effect of such bending on thepiston action is as follows: It being understood that the piston is inthe nature of a disk, and is made up of one or more disks of suitablepliable material, presently described, it will now be assumed that thepiston 5 is at the top dead center, as shown in Fig. 8, and is about tocommence its down stroke. As the crank-pin swings over its top deadcenter, the angularity of the piston 5 is progressively increased as itcontinues its down-stroke, and reaches a maximum when the crank 2reaches its horizontal position as shown in Fig. 5. This progressiveincrease in angularity of the piston has definitely opened up two spaces8 on diametrically opposite sides of the piston between the edge of thepiston and the wall of the cylinder 8. These two openings 8 produce thesame effect as open valves and, permit the air to pass by the piston andinto the cylinder during its down or intake stroke.. As the crank 2swings past its horizontal position, on its down or intake stroke, theangularity of the piston progressively diminishes and the extent of the.openings 8 progressively diminishes until the crank 2 swings past itslower dead center, as shown in Fig. 6, and starts the piston on itsupward or working stroke, at which time the angularity of the piston 5becomes zero; and the air which has passed by the piston on its down orintake stroke is confined in the cylinder to be compressed or suitablydischarged by the upward or compression stroke of the piston. As thecrank-pin 3 reaches its horizontal position on this upstroke (Fig. '7),the maximum angularity of the piston 5 occurs. But this maximum is onlyonethird the maximum angularity which the piston assumed on its down orintake stroke (Fig. 5). This angularity of the piston (Fig. 7) is soslight that the pliability and resiliency of the piston materialpractically closes the cylinder so that no leakage of air past thepiston has been noted. As, however, the crank-pin 3 swings past itshorizontal position, the angularity of the piston progressivelydiminished until it again becomes zero just before the crank pin 3reaches its top dead center, at which time compression of the air in thecylinder is greatest. As the crank-pin 3 reaches its top dead center.(Fig. 8) the piston 5 has begun to assume the angularity whichprogressively increases on its downstroke to its maximum (Fig. 5) asheretofore described. The result of this construction and resultingpiston action is that no air-intake valve is required, but only a simpleoutlet check valve need be provided to prevent the air which has beendischarged on the compression stroke of the piston from passing backinto the cylinder, as will be presently described.

From an examination of the diagrammatic Figures 5 to 8, it becomesobvious that since the piston action depends on the fact that the pistonis established in an angular position in the cylinder in the mannerdescribed, which angularity is substantially greater during its outwardor intake stroke than during its inward or working stroke, suchangularity of the piston may be obtained by forming the end surface ofthe piston rod on the desired angle and without bending the piston, sothat when the piston is seated on such angularly formed end, the pistonwill assume the same angle as is given the end surface of the piston. Inthis case the piston rod is initially formed to support the piston atthe desired angle, or the piston rod is initially formed straight andsubsequently bent to dispose the piston at the desired angularity. Ineither instance, the piston rod may be said to be shaped to rigidlysupport the piston angularly thereto, and the piston may be described ashaving its transverse plane tilted with respect to the transverse planeof the cylinder to a lesser extent during its inward or working strokethan during its outward or intake stroke.

Referring now to Figs. 1 to 4 which illustrate two embodiments of theapplication of this pump action to operative devices, it will be seenfrom Fig, 1, that the pump 9 is mounted directly on the electric drivingmotor I0 so that the pump and motor becomes a unitary device. For thispurpose, a worm-gear drive, such as is disclosed in U. S. Patent No.2,082,446, may be conveniently employed. Suitably secured to the frontend I I of the motor I0 is a bracket l2 which includes two parallel andhorizontally projecting arms I3, bored out to receive a horizontaldriven shaft I. Upon the motor or armature shaft I3 is secured asuitable worm I6 which meshes with a suitable worm wheel or gear I]fixed on the horizontal driven shaft I between the two arms I3 of thebracket I2. Any suitable speed reduction may be obtained from such wormand gear.

Since reciprocating pumps lose efliciency if operated at high speed, Ihave found that a speed of about 400 R. P. M, for the horizontal drivenshaft I, which, in this case becomes the pump shaft, is entirelysatisfactory. To accomplish this reduction of the motor speed, for theparticular motor used, an eight thread worm I8 as shown in Fig. 1 isemployed while the worm wheel or gear with which the worm meshes has 36teeth giving a. reduction ratio of 4 to 1.

In the particular pump or compressor illustrated in Figs. 1 and 2, themotor I0 is of the four pole shaded pole type of a fractional H. P. ofwhile the pump or compressor which is double acting has pistons ofdiameter with strokes, this data being stated merely as an example andnot as a limitation.

Referring further to Fig. 1, there is provided in each of the bracketarms I3 at points adjacent to but in rear of the horizontal driven shaftI, a vertical hole, in each of which is mounted a vertical post I8, eachof which posts is secured in its bracket arm I3 by nuts I9 bearing onthe underside of the bracket arms.

Secured on the upper ends of the posts I8, as by nuts 20 is a flathorizontal plate 2|, which forms the heads for the two pump cylinders,to which plate 2I, the cylinders 6 may be effectively attached as bysoldering, brazing'or welding, or in any other approved manner.

Secured on each end of the driven shaft I, is a crank 2 fixed thereon byset screws 23, and in each crank 2 is a crank-pin 3.

4 indicates the piston rods mounted on the crank-pins 3, and 5 indicatesthe pistons which are rigidly secured to the tops of the piston rods 4.In the example shown, each piston 5 includes a thin disk of stiff fibreof about diameter and two thin disks 25 of leather or other suitableflexible and resilient material each in diameter and a thin metallicdisk 26 of about diameter, the fibre disk 24 and metal disk 26 havingfor their purpose to stiffen the body portions of the two thin flexibledisks 25, between which first mentioned disks, the flexible disks areclamped, and at the same time permitting the peripheral edges of thedisks 25 a flexible and resilient contact with the cylinder wall. Thepistons 5, so constructed, are rigidly secured to the ends of thepiston-rods, as by a machine screw 21 threaded into the end of eachpiston rod 4.

Suitably mounted on the top of the cylinderhead-plate 2| and directlyabove each cylinder 6, is, what may be termed a valve-chest 28. This ispreferably square in cross section, as shown in Fig. 2, and has formedtherein a vertical hole 29 reduced near its lower end to form a seat fora ball 30, the reduced bore 3I also passing through thecylinder-head-plate to form a port 3I through which air is dischargedfrom the pump cylinder. Connecting each of the valve-chests 28 is a tube32, and extending from the outer ends of each valve chest is a shorttube-33, to which flexible tubings may be connected. By

this construction. the valve-controlled outlet ports Ii of each cylinderare connected, so that the discharge from both cylinders may be causedto pass out through only one end-tube II by suitably closing up theother end-tube II, or if desired, a simple relief valve (not shown)maybe connected to one end-tube II, so as to relieve as little or asmuch of the pressure passing from the other end-tube as may be desired.

As will appear from Fig. 2, the piston rods 4 are bent to secure thepiston action which has been hereinbefore dcscribedwith respect to thediagrammatic Figs. 5 to 8, while the armature shaft It may extendthrough the rear end of the motor casing upon which 'a cooling fan Ilmay be mounted, since in some applications of the pump, the operation iscontinuous over a long period of time.

Referring to Fig. 3, it will be seen that in the embodiment illustrated,the pump is driven by a friction drive which includes a large drivenwheel or pulley II having a crowned peripheral surface I and mounted ona shaft I. In this case, I prefer to dispense with a crank, and mountthe crank-pin I directly on the driven wheel or pulley I5. I! indicatesthe motor, and I5 indicates the motor or armature shaft. Mounted on thisshaft is the crowned driving pulley II having two flanges I9.

indicates the friction ring, which may be made of a suitable rubber, orsynthetic rubber or other resilient and wear resisting composition. Thisring 40 has an internal diameter sufflcient to permit its being forcedover the outside flange I9 of the crowned driving pulley II and 1 bepositioned between the two crowned surfaces of the driving and drivenpulleys II and I5. Any suitable means (not shown) may be provided tomaintain the motor Ill and its driving pulley II in position so as toexert sufllcient pressure upon the friction ring 40 to cause effectivefrictional contact between the driving pulley II and the inside surfaceof the ring 40, and between the outside surface of the ring 40 and thecrowned surface of'the driven wheel or pulley I5, so that an effectiverolling contact may be maintained between the coacting surfaces of allthree of these elements.

It is preferable that the width and thickness of the friction ring Illbe such that, in operation, it will maintain its normal annular form byhaving suflicient inherent rigidity. This will result in smootheroperation with absence of vibration.

It is also desirable to prevent contact of the sides of the frictionring with the side flanges 39 of the driving pulley II, as such contactwould create a slight drag and prevent a perfect rolling contact of thepulley II on the inner surface of the friction ring. In order toaccomplish an eifective centering of the friction ring 40 on the pulley38 and between the two side flanges thereof, the surface of drivingpulley II is crowned,

as shown, while the coacting surface of the driven wheel or pulley 35may also be crowned as shown for the same purpose.

Any desired gear ratio may be obtained, the effective diameter of thedriving elements of the device being the actual diameter of the crowneddriving pulley II plus the cross-section thickness of the friction ringIll.

The description of the pump elements shown in Figs. 1 and 2 apply to theexample shown in Fig. 3, except that in the single cylinder pump shownin this a re, the two short tubes I3 extend from the single Valve-chestII, to which tubes II, flexible tubes may be connected or a relief valvemay be connected to one of the tubes II for the same p rpose heretoforestated with respect to Figs. 1 and 2.

The object of the construction and arrangement of the rolling frictionring 40 as described is to obviate the disadvantages usually resultingfrom the provision of a resilient ring or 'cover fixed on the peripheralsurface of one or both of the contacting pulleys. If the surface of thedriven wheel or pulley II is provided with a flxed resilient cover forthe purpose of driving a fluctuating load such as the piston pumpillustrated, the wear on such cover is localized on one portion of theperiphery of the cover which is in contact with the driving pulleyduring the compression or working stroke of the piston. This, of course,results in an unevenwearing of the surface of the cover and an ultimateeccentricity thereof unfavorable to smooth and steady operation. On theother hand, if the driving pulley is surfaced with a resilient cover,the peripheral area of the same is so small that the wear is excessiveand the length of contact with the driven wheel or pulley is so shortthat slippage is prevented only by the application of greater pressurethan is favorable to the armature shaft and bearings. As opposed tothese disadvantages, the provision'of the solid friction ring 40 of much'greater diameter than the crowned driving pulley and rolling betweenthe driving and driven pulleys .provides that the points of contact ofthe periphery of the friction ring are constantly changing with respectto the contacting surface of the driven pulley so that the wear on thefriction ring is not localized on any particular portion of itsperiphery, while I the relatively great peripheral area of the frictionring results in the distribution of normal wear over a much greatersurface than is the case where the driving pulley is provided with asmall fixed frictional cover of relatively small peripheral area;

As an additional advantage, the length of frictional contact between thecrowned driving pulley I8 and the internal surface of the friction ring40 is much greater than if such driving pulley were in contact with aresiliently covered driven pulley, since in the former case, the contactis between the convex surface of the driving pulley and the concaveinner surface of the friction ring, while in the latter case the contactwould be between the convex surface of the driving pulley and the convexsurface of the driven pulley. These materially increased areas offrictional contact between the driving pulley and the friction ring andbetween the friction ring and the driven pulley result in more effectivefrictional contacts requiring the application of reduced pressurebetween the three coacting elements of the friction drive.

Having thus described the invention, it is apparent that the same may bechanged, altered or modified in the construction and arrangement of theparts without departing from its spirit and scope, and I consider myselfclearly entitled to all such changes and modifications as fall withinthe limit and scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is:

1. In an air pump or compressor, the combination with an electric motorhaving a worm on its armature shaft, a worm wheel or gear meshing withsaid worm, a driven shaft upon which said worm wheel or gear is fixed, abracket fixed on the motor casing for mounting the driven shaft, of apair of vertical posts mounted on the bracket, a cylinder-head-platehorizontally mounted on the upper ends of the vertical posts, a pair ofpump cylinders fixed to the underside of the cylinder-head-plate anddepending therefrom, a crank fixed on each end of the said driven shaft,each crank including a crank-pin, a piston-rod mounted on eachcrank-pin, and a check-valve-controlled discharge port for each pumpcylinder, the discharge ports of the two pump-cylinders being connectedby a common passage, a piston rigidly fixed on the upper end of eachpiston-rod, each of the piston-rods being positioned to dispose itsrigidly fixed piston in a plane angularly with relation to thelongitudinal axis of its cylinder, in such manner that during theoutward or intake stroke of the piston, the angularity of its transverseplane with relation to the longitudinal axis of its cylinder issubstantially greater than it is on its inward or working stroke,whereby on the outward or intake stroke of the piston, this greaterangularity of the plane of the piston is suflicient to create a spacebetween the piston and'the wall of the. cylinder to permit air to passby the piston and into the cylinder, while on the inward or workingstroke of the piston, the lesser angularity of the plane of the pistonwith relation to the longitudinal axis of its cylinder results in thepiston substantially closing the cylinder to retain the air therein anddischarge the same through its cylinder discharge port.

2. In an air-pump or compressor, the combination with an electric motorand its armature shaft, of a crowned driving pulley mounted on thearmature shaft, side flanges on the driving pulley, a driven pulleyhaving a crowned peripheral surface adjacent the crowned driving pulley,a friction ring of suitable resilient material having an internaldiameter greater than that of the crowned driving pulley and disposed onthe crowned driving pulley and between the crowned surface thereof andthe crowned surface of the driven pulley, whereby a rolling contact isestablished between the crowned driving pulley and the internal surfaceof the friction ring, and between the external surface of the frictionring and the crowned surface of the driven pulley, the friction ringbeing maintained centrally of the driving pulley by the coaction betweenthe two crowned surfaces of the two pulleys on the internal and externalsurfaces of the friction ring, the width and thickness of the frictionring being such as to impart enough rigidity to the ring to cause it tomaintain substantially into normal annular form in operation.

3. In an air pump or compressor, the combination with an electric motorand its armature shaft, of a crowned driving pulley mounted on thearmature shaft, side flanges on the driving pulley, a driven pulleyhaving its peripheral surface adjacent the crowned driving pulley, afriction ring of suitable resilient material and having an internaldiameter greater than that of the crowned driving pulley and disposedthereon between the crowned surface thereof and the adjacent surface ofthe driven pulley, whereby a rolling contact is established between thecrowned driving pulley and the internal surface of the friction ring,and between the external surface of the friction ring and the contactingsurface of the driven puliey, the friction ring being maintainedcentrally of the driving pulley by the coaction between the crownedsurface of the driving pulley and the internal surface of the frictionring.

4. In a friction drive for air pumps and the like, a driving pulleyhaving side flanges, a driven pulley having its peripheral surfaceadjacent the driving pulley, the adjacent surface of one of the pulleysbeing crowned, and a friction ring of greater internal diameter than thedriven pulley and disposed thereon between and in contact with theadjacent surfaces of the two pulleys, the friction ring being maintainedcentrally of the driven pulley by the coaction between the contactingcrowned surface of one of the pulleys with the friction ring; A 5. In anair-pump or compressor, the combination with an electric motor having aworm on its shaft, a worm wheel meshing with said worm, a driven shaftupon which said worm wheel is fixed, a bracket fixed on the motor casingfor mounting the driven shaft, of posts mounted on the bracket, acylinder-head-plate mounted on the outer ends of the posts, a pair ofpump cylinders fixed on the cylinderhead-plate, a crank fixed to eachend of the driven shaft, each crank including a crank-pin, a piston rodmounted on each crank-pin, a piston rigidly fixed on the upper end ofeach piston-rod and disposed for operation in the said pump cylinders, adischarge port and check valve for each pump cylinder, the latterpreventing return of air back through the discharge port into the pumpcylinder, the transverse plane of each piston being tilted with respectto the transverse plane of its cylinder to a lesser extent during itsinward or working stroke than during its outward or intake stroke forthe purposes described.

6. In an air-pump or compressor, the combination with an electric motorhaving worm gearing and provided with a bracket fixed on the motorcasing and having a driven shaft mounted in said bracket, of a pair ofpump cylinders and means for mounting them on the bracket, a crank andcrank pin on each end of the driven shaft, a piston rod mounted on eachcrank pin, a piston rigidly fixed on each piston rod and disposed foroperation in the pump cylinders, and a discharge port and check valvefor each pump cylinder, the transverse plane of each piston being tiltedwith respect to the transverse plane of its cylinder to a lesser extentduring its inward or working stroke than during its outward or intakestroke for the purposes described.

7. In an air-pump or compressor, the combination with an electric motorhaving worm gearing and provided with a bracket fixed on the motorcasing and having a driven shaft mounted in the said bracket, of apair'of pump cylinders and means for mounting them on the bracket,piston rods and pistons rigidly fixed on the rods and disposed foroperation in the pump cylinder and actuated by the driven shaft, thetransverse plane of each piston being tilted with respect to thetransverse plane of its cylinder to a lesser extent during its inward orworking stroke than during its outward or intake stroke for the purposesdescribed.

8. In an air-pump or compressor, the combination with an electric motorhaving worm gearing and provided with a bracket fixed on the motorcasing and having a driven shaft mounted in the said bracket, of a pumpcylinder and means for mounting it on the bracket, a piston rod andpiston rigidly fixed thereon and disposed for operation in the pumpcylinder and actuated by the driven shaft, the transverse plane of thepiston being tilted with respect to the transverse plane of the cylinderto a lesser extent during its inward or working stroke than during itsoutward or intake stroke for the purposes described.

9. In an air-pump or compressor, the combination with an electric motorhaving a driven shaft and worm gearing for driving the shaft andprovided with a bracket for the driven shaft fixed on the motor casing,of vertical posts mounted on the bracket, a cylinder-head-platehorizontally mounted on the upper ends of the vertical posts, a pair ofpump cylinders fixed to the unj derside of the cylinder-head-plate anddepending therefrom, a crank and crank-pin on each end of the drivenshaft, a piston rod mounted on each crank-pin, pistons disposed foroperation in the pump cylinders and actuated therein by the piston rods,a discharge port and check valve for each pump cylinder, the latterpreventing return of air back through the discharge port into the pumpcylinder, and means for effecting communication between the dischargeports of the pump cylinders.

10. In an air-pump or compressor, the combination with an electric motorhaving a driven shaft and worm gearing for driving the shaft andprovided with a bracket for the driven shaft fixed on the motor casing,of posts mounted on the bracket, a cylinder-head-plate mounted on theposts, a pair of pump cylinders fixed on the cylinder-head-plate, acrank and crank pin on each end of the driven shaft, a piston-rodmounted on each crank-pin, pistons on the piston rods disposed foroperation in the pump cylinders and actuated therein by the piston rods,a discharge port for each pump cylinder and means for preventing returnof air backthrough the discharge ports of the pump cylinders.

11. In an air-pump or compressor, the combination with an electric motorhaving a driven shaft and worm gearing for driving the shaft,

and provided with a bracket for the driven shaft fixed to the motorcasing, of a pair of pump cylinders and means for mounting them on thebracket, a crank and crank-pin on each end of the driven shaft, apiston-rod mounted on each crank-pin, pistons on the piston rodsdisposed for operation in the pump cylinders and actuated by the pistonrods, a discharge port for each cylinder and means for preventing returnof air back through the discharge ports of the pump cylinders.

12. In an air-pump or compressor, the combination with an electric motorand gearing, which includes a Worm gear on the motor shaft, a drivenshaft, a bracket fixed on the motor casing, the bracket having armsextending outwardly from the motor casing for mounting the driven shafttransversely of the motor shaft and a worm-wheel fixed on the drivenshaft for meshing engagement with the worm on the motor shaft, of a pairof pump cylinders and means for mounting them on the said bracket armsin such manner that the bracket arms which mount the driven shaft alsomount the pump cylinders, pistons disposed for operation in the pumpcylinders and piston rods operated by the driven shaft for actuating thepistons.

13. In an air-pump or compressor, the combination with an electric motorand gearing, which includes a worm gear on the motor shaft, a drivenshaft, a bracket fixed on the motor casing, the bracket having armsextending outwardly from the motor casing for mounting the driven shafttransversely of the motor shaft and a worm-wheel fixed on the drivenshaft for meshing engagement with the worm on the motor shaft, a pumpcylinder and means for mounting it on the said bracket arms in suchmanner that the bracket arms which mount the driven shaft also mount thepump cylinder, a piston disposed for operation in the pump cylinder, anda piston rod operated by the driven shaft for actuating the piston.

CHARLES HUGH DUFFY.

